Spring jaw chuck



Oct. 31, 1961 M. 1.. BENJAMIN SPRING JAW CHUCK Filed May 7, 1959 INVENTOR. MILTON L. BENJAMIN BY U'M'w, 'povmdy ATTORNEYS United States Patent 3,006,654 SPRING JAW CHUCK Milton L. Benjamin, Shaker Heights, Ohio, assignor to Erickson Tool Company, Solon, Ohio, a corporation of Ohio Filed May 7, 1959, Ser. No. 811,708 14 Claims. (Cl. 279-23) The present invention relates generally as indicated to a spring jaw chuck and more particularly to a spring jaw chuck in which the jaws are in the form of U-shapecl spring members, each having one leg fixedly mounted to the chuck and the other leg resiliently movable, by yielding of the leg-connecting portion, into and out of gripping engagement with a workpiece.

It is a principal object of this invention to provide a spring jaw chuck which is economical to manufacture and which is arranged to securely and coaxially grip workpieces therein.

It is another object of this invention to provide a spring jaw chuck in which the workpiece gripping jaws are mounted on spring members which are adapted to be resiliently deflected. It is another object of this invention to provide a spring jaw chuck which is adapted to be pneumatically actuated to workpiece-releasing position and adapted, by the re siliency of the jaw mounting members, to spring back to workpiece-gripping engagement upon venting or rel asing of the air pressure from the chuck.

It is another object of this invention to provide a spring jaw chuck of the character indicated in which each of a plurality of jaw mounting members is of generally U-shaped radial cross-section including parallel radially extending legs, one of which is adapted to be secured to the chuck proper and the other of which is adapted to mount a radially adjustable chuck jaw and to he resiliently deflected about a curved yieldable leg-connecting portion.

It is another object of this invention to provide a spring jaw chuck of the character indicated in which the direction of the grain of the metal of the generally U-shaped spring members is lengthwise of the legs and lineally around the curved yieldable leg-connecting portions.

Other objects and advantages of the present invention will become apparent as the following description proceeds.

To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail a certain illustrative embodiment of the invention, this being indicative, however, of but one of the various ways in which the principle of the invention may be employed.

In said annexed drawing:

FIG. 1 is a front elevation view of a spring jaw chuck embodying the present invention;

FIG. 2 is cross-section view taken substantially along the line 2-2, FIG. 1;

FIG. 3 is a fragmentary top plan view showing one of the spring jaw assemblies; and

FIG. 4 is a side elevation view of one of the spring jaw elements by itself and showing the direction ot the grain in the metal thereof.

The spring jaw chuck 1 herein illustrated comprises a base plate 2 which is formed with peripheral slots 3 by which it may be secured on a machine spindle, table, or the like, said base plate 2 including an axially extending tubular portion or cylinder 4 in which the piston 5 is reciprocable. Said base plate 2 is also formed with a central threaded port 6 to which an air pressure supply line is adapted to be connected by way of a suitable control valve which alternately permits air pressure to enter and to be vented from the space 7 in the cylinder 4.

Secured to the flanged end of the cylinder 4, as by means of the screws 8, is a jaw mounting plate 9 which also serves as the closure for the cylinder 4, said jaw mounting plate 9 being formed with a central opening 10 through which projects the tubular jaw actuator 11 which has its inner end telescoped over a boss 12 formed on the piston 5 and in abutting engagement with the outer side of the piston 5.

Mounted on the jaw mounting plate 9 are a plurality of radially disposed generally U-shaped spring members '14. In this case, there are shown three such spring members 14 equally spaced about the axis of the chuck. Each spring member 14 has an inner radially extending leg 15 which is securely mounted in a radial groove formed on the outer face of the plate 9 by means of the screws 16 and pin 17. The outer leg 18 of each spring member 14 is parallel to the leg 15 and extends radially inward therebeyond for engagement by the outer end of the tubular actuator 11. The semicircular leg connecting portion 19 of each spring member 14 is of reduced radial cross-section thickness and, as best shown in FIG. 4, the grain of the metal preferably extends lineally along the respective legs 14 and 18 and lineally around the curved leg connecting portion 19. In other words the spring members 14 are machined from straight lengths of bar stock and are bent to U-shaped form.

The outer leg 18 of each spring member is formed with a radial groove or slideway in which a workpiece gripping jaw 20 is mounted for radial adjustment.

Each jaw 20 is formed with a pair ocE openings therethrough which are of greater radial extent than the diam eters of the shanks of the screws 21 by which they are secured to the outer leg 18 of the respective spring member 14 whereby each jaw 20 may be radially adjusted to position its workpiece-engaging inner end 23 at a prescribed distance from the axis of the chuck. Each spring member 14 also has formed in its outer leg 18 a conical recess 24 in which the point of a setscrew 25 is adapted to be seated so as to lock each jaw 20 in desired radially adjusted position. The setscrew 25 is prevented from loosening by the lockscrew 26.

The jaw mounting plate 9 also carries a plurality of stop screws 27 to assure axial location of a workpiece with respect to the chuck 1 and, of course, it is to be understood that these stop screws 27 may be arranged to mount a spider-like workpiece locator which has a stop face disposed in the space within the jaw actuator -11 for abutment by the inner end of a cylindrical or like workpiece.

From the :foregoing, it can be seen that when air under pressure is admitted through the port 6 into the space 7' in the cylinder 4, the piston 5 and the actuator 11 will be urged toward the right, as viewed in FIG. 2. Such movement of the tubular actuator 11 will cause the outer legs 18 of the spring members 14 to swing out about the resilient connecting portions 19, whereby the workpieceengaging inner ends 23 of the jaws 20 will be swung outwardly to workpiece-releasing position. With the spring jaw assemblies thus flexed, a workpiece may be positioned within the inner ends 23 of the jaws 20 and in abutting engagement with the stop screws 27 which are fixed to the rigid jaw mounting plate 9. Now, when the air pressure in the space 7 of the cylinder 4 is vented, the spring members 14 will tend to spring back to their original positions where the legs 15 and 18 there of are parallel and, in so doing, the jaws 20 will be swung inwardly so that the inner ends 23 thereof will frictionally engage and center the workpiece with respect to the axis of the chuck. It is to be noted that the radial gripping action is many times multiplied due to the fact that the axial component of the spring-back of the spring members 14 is several times the radial component. Also, although the axial force exerted by the actuator 11 may be relatively small to swing the legs -18 out to release a workpiece, the curved leg connecting portions 119 are substantially inflexible insofar "as radial outward forces at theinner ends 23 of the jaws 20 are concerned whereby huge gripping forces are obtainable by the springback action of the spring members.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims, or the equivalent of such, be'employed.

. I therefore particularly point out and distinctly claim as my invention:

Q 1. A chuck comprising a jaw mounting plate; a plurality. of workpiece gripping jaw assemblies on said plate, each comprising a generally U-shaped spring member which has a first leg secured to said plate, a second leg secured to a jaw member disposed to engage a workpiece, and a resilient leg-connecting portion; and means operative to flex said spring member about its leg-connecting portion to move said second leg relatively away from a workpiece.

2. The chuck of claim 1 wherein said means acts on the free end of said second leg to swing it laterally relative to said first leg about said leg-connecting portion.

'3. A chuck comprising a base plate; a jaw mounting plate secured to said base plate and defining a cylindrical chamber therewith; a piston reciprocable in said chamber; a circular series of workpiece gripping jaw assemblies secured on said jaw mounting plate including generally U-shaped spring members, each spring member including a first radially extending leg secured on said jaw mounting plate, a second radially extending leg having a free end secured to a jaw member disposed to engage a workpiece, and a resilient leg-connection portion; and an actuator engaged between said piston and said second legs of said spring members efiective, when fluid under pressure is admitted into said chamber, to swing said second legs away from said first legs about said re silient leg-connecting portions in a direction suchthat said jaw members are moved relatively away from a workpiece, said jaw members springing back to workpiece engaging positions upon release of the fluid pres-.

sure in said chamber.

4. The chuck of claim 3 wherein said free ends are disposed radially inward of the free ends of said first legs, said jaw mounting plate having a central opening through which said actuator extends to transmit force from said piston to said second legs.

5. The chuck of claim 3 wherein said jaw members are radially adjustably secured on the respective second legs.

6. The chuck of claim 3 wherein the grain of the metal of said spring members extends lengthwise of said legs and of said leg-connecting portions from one leg to the other of the respective spring members.

7. The chuck of claim 3- wherein the leg-connecting portion of each spring member is of curved form substantially tangent to the respective legs so as to be relatively flexible in response to a force that tends to spread apart the free ends of said legs but relatively inflexible in response to a gripping force that acts lengthwise of said second leg.

8. A spring jaw member for a chuck comprising a generally U-shaped body of spring metal having a pair of generally parallel legs and asresiliently deformable legconnecting portion, one leg being longer than the other whereby a force may be, applied thereon to resiliently spread apart the free ends of said legs by yielding of said leg-connecting portion.

9. The spring jaw member of claim 8 wherein said leg-connecting portion is of curved form substantially tangent to the respective legs.

10. The spring j-aw member of claim 9 wherein said leg-connecting portion is of thickness less than the thickness of the respective legs.

11. The spring jaw member of claim10 wherein the grain of the metal extends lengthwise of said legs and of said leg-connecting portion.

12; A chuck comprising a jaw mounting plate; a plurality of workpiece gripping jaw assemblies on said plate, A

at least one of which comprises a generally U-shaped spring member which has a first leg secured to said plate, a second leg secured to a jaw member disposed to engage a workpiece, and a resilient leg-connecting portion; and means operative to flex said spring member about its leg-connecting portion to move said second leg relatively away from a workpiece, said legs being generally parallel to each other and extending radially of the chuck when said spring member is in unflexed condition. 7

13. The chuck of claim 12 wherein the grain of the metal of said spring member extends lengthwise of said legs and of said leg-connecting portion from one leg to the other.

14. The chuck of claim 12 wherein said leg-connecting portion is of curved form substantially tangent to the respective legs so as to be relatively flexible in response to a force that tends to spread apart the free ends of said legs but relatively inflexible in response to a gripping force that acts lengthwise of said second leg.

References Cited in the file of this patent UNITED STATES PATENTS 1,070,221 Wollmann Aug. 12, 1913 1,903,964 Faust Apr. 18, 1933 2,709,599 Mann May 31, 1955 2,801,860 Getts Aug. 6, 1957 2,821,400 Hohwart et al. Jan. 28, 1958 

